2012年国际脊柱放射外科学会红皮脊髓立体定向放疗靶区指南

Spinal stereotactic radiosurgery (SRS), also known as spinal stereotactic body radiation therapy, is being increasingly used in the management of metastatic spine tumors. SRS uses a combination of image-guided technologies to remediate interand intra-fraction motion and advanced inverse treatment-planning algorithms to achieve highly conformal dose distributions. This permits delivery of treatment plans with steep dose gradients between target volumes and adjacent organs at risk. This is particularly desirable for treating spinal tumors, where local failure is catastrophic and tumors abut sensitive critical normal tissues such as the spinal cord and esophagus. Approximately 50% of radiation oncologists currently incorporate spinal SRS into their practice, and there is widespread acceptance of SRS in the neurosurgical community.

Large retrospective single-institution studies demonstrate the efficacy of spinal SRS with durable local control, progression-free survival, and palliation rates of approximately 70%-90% in patients receiving de novo treatment, retreatment after prior radiation, and treatment postoperatively after surgical resection. Radiosurgery has also shown potential for decompressing spine metastases with epidural extension causing spinal cord compression. The results of 2 prospective studies for spinal radiosurgery have recently been reported, both concluding that spinal radiosurgery is feasible, effective, and indicated as an expanding first-line option in properly selected patients with spinal metastases. Radiation Therapy Oncology Group 0631 is ongoing and is accruing to the phase III component, which compares up to 18 Gy of spinal SRS with a control arm of 8 Gy, both delivered in a single fraction.

Although there are limited published guidelines regarding spine SRS indications and patterns of practice, consensus definitions for target volumes have yet to be established. Consensus definitions are necessary to standardize the nomenclature and delivery of spinal radiosurgery and enable comparison of results from different institutions, treatment platforms, and dose-fraction schedules. Patterns of failure analysis have identified marginal failures beyond the conformal targeted volume as a primary pattern of recurrence, highlighting the need for accuracy in target volume delineation. Identifying the correct clinical tumor volume is of particular importance because the steep dose gradients associated with SRS result in subtherapeutic doses within millimeters of the planning target volume, and the adjacent normal tissues are at risk of injury from high dose-perfraction regimens.

The purpose of this report is to provide consensus guidelines for target volume definition for spinal metastases when using SRS.